- Email: [email protected]
Comparison of two selective media for the isolation of Campylobacter species from a pediatric population in Mexico
NOTES
Comparison of Two Selective Media for the Isolation of Campylobacter species from a Pediatric Population in Mexico Patricia Arzate Barbosa, Rafael Garcia Gonzalez, Eliut Ponce Nava, and Irving Nachamkin
Two selective media for the isolation of Campylobacter species, a blood containing medium (CampyBAP) and blood-free, charcoal based formulation (CCDA) were compared for the ability to isolate Campylobacter species during a 1-year period. Of the 1,132 stool samples cultured during the study, 42 Campylobacter species were recovered using both media
(3.7% yield). CCDA was better than CampyBAP for isolating C. jejuni subsp jejuni (18/20 vs 8/20, P ⫽ 0.002) and for all isolates, CCDA was superior over CampyBAP (39/42 vs 13/42, P ⬍ 0.0001). Overall, CCDA is a superior medium compared with CampyBAP for isolating Campylobacter species in our study population. © 1999 Elsevier Science Inc.
Campylobacter jejuni subsp. jejuni is one of the most common causes of bacterial diarrhea worldwide. In developing countries in particular, the incidence of C. jejuni infections is very high, several orders of magnitude higher than that seen in developed countries (Taylor 1992). Campylobacter species can be isolated from fecal specimens using a variety of selective media including blood-containing and bloodfree formulations (Nachamkin 1999). Several studies have been published comparing different media formulations (Endtz et al. 1991; Gun-Monro et al. 1987; Piersimoni, et al. 1995), however, these studies have been performed in developed countries with predominantly adult populations. The purpose of this study was to compare the blood-containing Bla-
ser formulation, CampyBAP (Blaser et al. 1978), a commonly used medium in clinical laboratories, with a blood-free, charcoal-based medium, CCDA (Hutchinson & Bolton 1984) for the ability to isolate Campylobacter species from patients seen in a pediatric hospital with gastroenteritis. The study was conduced at the Instituto Nacional de Pediatria (INP), a major referral hospital in Mexico City from January through December, 1997. All stool samples were submitted to the Bacteriology Laboratory from various hospital clinics using Cary-Blair transport medium (Nachamkin 1999). CampyBAP was used routinely for isolation of Campylobacter species and during the study period, CCDA was also included and set up in parallel with the other cultures. CampyBAP was prepared in the laboratory according to manufacturer’s instructions using Campylobacter Agar Base (Difco, Mexico City), and supplement B (Difco, Mexico City). CampyBAP is a blood-containing medium containing the following selective antimicrobial agents: vancomycin, polymyxinB, trimethoprim, cephalothin, and amphotericin B. CCDA was also prepared in the laboratory using Campylobacter Blood Free Selective
From the Laboratorio de Bacteriologia Division Saditra, Instituto Nacional de Pediatria, Mexico City, Mexico (PAB, RGG, EPN) and Department of Pathology and Laboratory Medicine (IN), University of Pennsylvania School of Medicine, Philadelphia, PA 19104-4283. Address reprint requests to Dr. Irving Nachamkin, University of Pennsylvania School of Medicine, Department of Pathology & Laboratory Medicine, 4th Floor, Gates Building, 3400 Spruce Street, Philadelphia, PA 19104-4283. Received 5 January 1999; revised and accepted 12 April 1999.
DIAGN MICROBIOL INFECT DIS 1999;34:329 –332 © 1999 Elsevier Science Inc. All rights reserved. 655 Avenue of the Americas, New York, NY 10010
0732-8893/99/$–see front matter PII S0732-8893(99)00047-4
P.A. Barbosa et al.
330 Agar Base (Unipath Oxoid, Mexico City), and CCDA Selective Supplement (SR 155, Unipath Oxoid, Mexico City) according to manufacturers instructions. CCDA is a blood-free, charcoal-based medium whose main selective ingredient is cefoperazone. Both media were prepared freshly each week and stored at 4°C until use. New batches of media were tested with a quality control strain of C. jejuni to test the ability of media to support the growth of Campylobacter. Samples were plated to both media and plates incubated at 42°C under microaerophillic conditions (CampyGen Gas Generator Paks, Unipath) for 2 days. Plates showing no growth after 2 days were reincubated for an additional 2 days before reporting as negative. Initial identification of Campylobacter species was based on colonial characteristics, microscopic morphology, and oxidase reaction. Most isolates were identified to species using oxidase reaction, catalase production, ability to hydrolyze sodium hippurate, nitrate reduction, and nalidixic acid/cephalothin disc identification tests (Nachamkin 1999). Isolates were also tested using a latex agglutination assay (ID Campy, Integrated Diagnostics, Baltimore, MD), which has been shown to be specific for C. jejuni subsp. jejuni, C. coli, and C. lari (Nachamkin & Barbagallo 1990). Some isolates were non-viable on subculture after initial isolation and were only characterized based on colony morphology, gram-stain, and oxidase reactions. For this study, these isolates were classified as Campylobacter species. Statistical analysis was performed using Fishers exact test to compare isolation proportions on the two media with GraphPad Prism 2.0 (GraphPad Software, San Diego, CA). From January to December 1997, 1,132 stool samples were processed for the isolation of enteric pathogens including Campylobacter species. Enteropathogenic E. coli serotypes were the most common isolates from the study population (7.5%), followed by Shigella (3.5%), Salmonella (2%), Aeromonas (0.8%), and Plesiomonas (0.1%). Using the two culture media, 42 patients had a stool culture positive for any Campylobacter species; 52.4% were isolated from patients less than 1 year of age (Table 1). Nearly 84% of the isolates were obtained from patients less than 3 years of age. These results are consistent with previous studies in Mexican children (Calva et al. 1988; Ruiz-Palacios et al. 1990) showing that the highest rate of isolation of Campylobacter is during the first year of life. The overall yield for Campylobacter was 3.71%, with 39 isolates recovered using CCDA medium compared with 13 using CampyBAP medium ( p ⬍ 0.0001) (Table 2). CCDA showed higher recovery of C. jejuni subsp. jejuni compared with CampyBAP (18/20 vs 8/20, respectively, p ⫽ 0.002). Although not fully identified to species, CCDA
TABLE 1 Frequency of Campylobacter Isolated from Pediatric Patients According to Age Age Group 0–1 1–2 2–3 3–4 4–5 5–6 Total
No. Isolates (Percent) 22 (52.4) 8 (19) 5 (11.9) 4 (9.5) — 3 (7.2) 42
showed higher recovery for isolates classified as Campylobacter species compared with CampyBAP (16/19 vs 3/19, p ⬍ 0.0001). There were no differences in the proportion of patients based on gender and isolation on CCDA (20 males, 19 females) or CampyBAP (7 males, 6 females). The results of this study are consistent with several previous studies showing that blood-free, charcoal-based medium such as CCDA is an excellent medium for the isolation of Campylobacter species from fecal samples (Endtz et al. 1991; GunMonro et al. 1987). Remarkably, CCDA recovered threefold more isolates than CampyBAP in the current study. CampyBAP is a blood containing medium containing a variety of antimicrobial agents including cephalothin. Cephalothin and other antibiotics, such as colistin and polymyxin B present in selective media may be inhibitory to some strains of C. jejuni and C. coli (Goossens et al. 1986; Ng et al. 1985; Ng et al. 1988) and will inhibit the growth of C. fetus subsp. fetus, thought to be under-isolated because of the use of cephalothin-containing media. Other species such as C. jejuni subsp doylei (Goossens et al. 1990), C. upsaliensis (Goossens et al. 1990), A. butzleri (Kiehlbauch et al. 1992; Kiehlbauch et al. 1991) generally will not grow on cephalothin containing media. None of the isolates that were tested with cephalothin disks in the current study appeared to be cephalothin susceptible so it is unlikely that the poor recovery of Campylobacter on CampyBAP was attributable to antimicrobial susceptibility of the isolates to cephalothin. In addition to the improved recovery of C. jejuni subsp. jejuni, CCDA recovered other Campylobacter species significantly better than CampyBAP (18 vs 3, p ⫽ 0.003). The identity of these species is unknown, but based on the predominance of C. jejuni subsp. jejuni as a cause of diarrheal disease, most of these isolates were likely to be C. jejuni subsp. jejuni. Only a few studies have evaluated multiple media for isolating Campylobacter in a prospective manner. Endtz et al (1991) evaluated five different selective media including CCDA and CampyBAP. As a single
Isolation of Campylobacter Species
331
TABLE 2 Identification of Campylobacter Species Isolated on CCDA and CampyBAP Media Identification
No. Isolates
No. Isolated CCDA Only
No. Isolated CampyBAP Only
No. Isolated Both Media
C. jejuni subsp. jejuni C. jejuni subsp. doylei C. coli C. lari Campylobacter species Total
20 1 1 1 19 42
12 0 1 0 16 29
2 0 0 0 1 3
6* 1 1 2** 10**
* p ⫽ 0.0022; ** p ⬍ 0.0001.
medium, CCDA had slightly better recovery of Campylobacter sp. than CampyBAP (83% vs 75%, respectively) and CCDA was superior in terms of ability to suppress normal contaminating enteric flora. CCDA was also better in recovering C. coli compared with CampyBAP (72% vs 42%). Gun-Munro et al (1987) also evaluated several common media used for isolating Campylobacter sp. including CampyBAP and CCDA. Quantitative studies and recovery from simulated stool samples showed that CCDA had better recovery than CampBAP, 99% vs 41%, respectively and CCDA also had better selective properties. Cefoperazone, which is used in CCDA as a selective agent, has been shown to have excellent suppressive properties of enteric flora, especially Pseudomonas (Endtz et al. 1991; Goossens et al. 1986; Gun-Monro et al. 1987). Other factors may have contributed to differences found in the performance of CampyBAP versus
CCDA is this study. Powdered media and supplements were obtained from different commercial suppliers and unknown storage conditions for these products may have had some affect on the performance of the media. Despite these concerns, however, the improvement of CCDA medium over CampyBAP is consistent with previously reported studies. Finally, the diagnosis of Campylobacter infections is highly dependent on the type of selective medium used in the laboratory. Our study shows that compared with the blood containing medium, CampyBAP, CCDA was a superior medium for routine use. Clearly, CampyBAP is an unacceptable medium for the routine use of Campylobacter in our population. Whether CCDA is superior to other blood containing formulations, such as Skirrows, CampyCVA, or charcoal media such as CSM, needs to be investigated.
REFERENCES Blaser MJ, Cravens B, Powers BW, Wang WL (1978) Campylobacter enteritis associated with canine infection. Lancet ii:979–981. Calva JJ, Ruiz-Palacios GM, Lopez-Vidal AB, Ramos A, Bojalil R (1988) Cohort study of intestinal infection with Campylobacter in Mexican children. Lancet i:503–505. Endtz HP, Ruijs GJ, Zwinderman AH, van der Reijden T, Biever M, Mouton RP (1991) Comparison of six media, including a semisolid agar, for the isolation of various Campylobacter species from stool specimens. J Clin Microbiol 29:1007–1010. Goossens H, De Boeck M, Coignau H, Vlaes L, Van den Borre C, Butzler J-P (1986) Modified selective medium for isolation of Campylobacter spp. from feces: Comparison with Preston medium, a blood-free medium, and a filtration system. J Clin Microbiol 24:840–843. Goossens H, Vlaes L, De Boeck M, Pot B, Kersters K, Levy J, de Mol P, Butzler JP, Vandamme P (1990) Is “Campylobacter upsaliensis”: An unrecognized cause of human diarrhoea? Lancet 335:584–586. Gun-Monro J, Rennie RP, Thornley JH, Richardson HL, Hodge D, Lynch J (1987) Laboratory and clinical eval-
uation of isolation media for Campylobacter jejuni. J Clin Microbiol 25:2274–2277. Hutchinson DN, Bolton FJ (1984) Improved blood free selective medium for the isolation of Campylobacter jejuni from faecal specimens. J Clin Pathol 37:956–957. Kiehlbauch JA, Baker CN, Wachsmuth IK (1992) In vitro susceptibilities of aerotolerant Campylobacter isolates to 22 antimicrobial agents. Antimicrob Agents Chemother 36:717–722. Kiehlbauch JA, Brenner DJ, Nicholson MA, Baker CN, Patton CM, Steigerwalt AG, Wachsmuth IK (1991) Campylobacter butzleri sp. nov. isolated from humans and animals with diarrheal illness. J Clin Microbiol 29: 376–385. Nachamkin I. (1999) Campylobacter and Arcobacter. In: Manual of Clinical Microbiology. Eds. Murray PR, Baron EJ, Pfaller MA, Tenover FC, and Yolken RH. Washington, D.C.: ASM Press, pp. 716–726. Nachamkin I, Barbagallo S (1990) Culture confirmation of Campylobacter spp. by latex agglutination. J Clin Microbiol 28:817–818.
332
Ng L-K, Stiles ME, Taylor DE (1985) Inhibition of Campylobacter coli and Campylobacter jejuni by antibiotics used in selective growth media. J Clin Microbiol 22: 510–514. Ng L-K, Taylor DE, Stiles ME (1988) Characterization of freshly isolated Campylobacter coli strains and suitability of selective media for their growth. J Clin Microbiol 26:518–523. Piersimoni C, Bornigia S, Curzi L, De Sio G (1995) Comparison of two selective media and a membrane filter technique for isolation of Campylobacter species from
P.A. Barbosa et al.
diarrhoeal stools. Eur J Clin Microbiol Infect Dis 14: 539–542. Ruiz-Palacios GM, Calva JJ, Pickering LK, Lopez-Vidal Y, Volkow P, Pezzarossi H, West MS (1990) Protection of breast-fed infants against Campylobacter diarrhea by antibodies in human milk. J Pediatr 116:707–713. Taylor DN (1992) Campylobacter infections in developing countries. In: Nachamkin I, Blaser MJ, & Tompkins LS, Eds. Campylobacter Jejuni: Current Status and Future Trends. Washington, D.C.: American Society for Microbiology, pp. 20–30.
Comparison of Two Selective Media for the Isolation of Campylobacter species from a Pediatric Population in Mexico Patricia Arzate Barbosa, Rafael Garcia Gonzalez, Eliut Ponce Nava, and Irving Nachamkin
Two selective media for the isolation of Campylobacter species, a blood containing medium (CampyBAP) and blood-free, charcoal based formulation (CCDA) were compared for the ability to isolate Campylobacter species during a 1-year period. Of the 1,132 stool samples cultured during the study, 42 Campylobacter species were recovered using both media
(3.7% yield). CCDA was better than CampyBAP for isolating C. jejuni subsp jejuni (18/20 vs 8/20, P ⫽ 0.002) and for all isolates, CCDA was superior over CampyBAP (39/42 vs 13/42, P ⬍ 0.0001). Overall, CCDA is a superior medium compared with CampyBAP for isolating Campylobacter species in our study population. © 1999 Elsevier Science Inc.
Campylobacter jejuni subsp. jejuni is one of the most common causes of bacterial diarrhea worldwide. In developing countries in particular, the incidence of C. jejuni infections is very high, several orders of magnitude higher than that seen in developed countries (Taylor 1992). Campylobacter species can be isolated from fecal specimens using a variety of selective media including blood-containing and bloodfree formulations (Nachamkin 1999). Several studies have been published comparing different media formulations (Endtz et al. 1991; Gun-Monro et al. 1987; Piersimoni, et al. 1995), however, these studies have been performed in developed countries with predominantly adult populations. The purpose of this study was to compare the blood-containing Bla-
ser formulation, CampyBAP (Blaser et al. 1978), a commonly used medium in clinical laboratories, with a blood-free, charcoal-based medium, CCDA (Hutchinson & Bolton 1984) for the ability to isolate Campylobacter species from patients seen in a pediatric hospital with gastroenteritis. The study was conduced at the Instituto Nacional de Pediatria (INP), a major referral hospital in Mexico City from January through December, 1997. All stool samples were submitted to the Bacteriology Laboratory from various hospital clinics using Cary-Blair transport medium (Nachamkin 1999). CampyBAP was used routinely for isolation of Campylobacter species and during the study period, CCDA was also included and set up in parallel with the other cultures. CampyBAP was prepared in the laboratory according to manufacturer’s instructions using Campylobacter Agar Base (Difco, Mexico City), and supplement B (Difco, Mexico City). CampyBAP is a blood-containing medium containing the following selective antimicrobial agents: vancomycin, polymyxinB, trimethoprim, cephalothin, and amphotericin B. CCDA was also prepared in the laboratory using Campylobacter Blood Free Selective
From the Laboratorio de Bacteriologia Division Saditra, Instituto Nacional de Pediatria, Mexico City, Mexico (PAB, RGG, EPN) and Department of Pathology and Laboratory Medicine (IN), University of Pennsylvania School of Medicine, Philadelphia, PA 19104-4283. Address reprint requests to Dr. Irving Nachamkin, University of Pennsylvania School of Medicine, Department of Pathology & Laboratory Medicine, 4th Floor, Gates Building, 3400 Spruce Street, Philadelphia, PA 19104-4283. Received 5 January 1999; revised and accepted 12 April 1999.
DIAGN MICROBIOL INFECT DIS 1999;34:329 –332 © 1999 Elsevier Science Inc. All rights reserved. 655 Avenue of the Americas, New York, NY 10010
0732-8893/99/$–see front matter PII S0732-8893(99)00047-4
P.A. Barbosa et al.
330 Agar Base (Unipath Oxoid, Mexico City), and CCDA Selective Supplement (SR 155, Unipath Oxoid, Mexico City) according to manufacturers instructions. CCDA is a blood-free, charcoal-based medium whose main selective ingredient is cefoperazone. Both media were prepared freshly each week and stored at 4°C until use. New batches of media were tested with a quality control strain of C. jejuni to test the ability of media to support the growth of Campylobacter. Samples were plated to both media and plates incubated at 42°C under microaerophillic conditions (CampyGen Gas Generator Paks, Unipath) for 2 days. Plates showing no growth after 2 days were reincubated for an additional 2 days before reporting as negative. Initial identification of Campylobacter species was based on colonial characteristics, microscopic morphology, and oxidase reaction. Most isolates were identified to species using oxidase reaction, catalase production, ability to hydrolyze sodium hippurate, nitrate reduction, and nalidixic acid/cephalothin disc identification tests (Nachamkin 1999). Isolates were also tested using a latex agglutination assay (ID Campy, Integrated Diagnostics, Baltimore, MD), which has been shown to be specific for C. jejuni subsp. jejuni, C. coli, and C. lari (Nachamkin & Barbagallo 1990). Some isolates were non-viable on subculture after initial isolation and were only characterized based on colony morphology, gram-stain, and oxidase reactions. For this study, these isolates were classified as Campylobacter species. Statistical analysis was performed using Fishers exact test to compare isolation proportions on the two media with GraphPad Prism 2.0 (GraphPad Software, San Diego, CA). From January to December 1997, 1,132 stool samples were processed for the isolation of enteric pathogens including Campylobacter species. Enteropathogenic E. coli serotypes were the most common isolates from the study population (7.5%), followed by Shigella (3.5%), Salmonella (2%), Aeromonas (0.8%), and Plesiomonas (0.1%). Using the two culture media, 42 patients had a stool culture positive for any Campylobacter species; 52.4% were isolated from patients less than 1 year of age (Table 1). Nearly 84% of the isolates were obtained from patients less than 3 years of age. These results are consistent with previous studies in Mexican children (Calva et al. 1988; Ruiz-Palacios et al. 1990) showing that the highest rate of isolation of Campylobacter is during the first year of life. The overall yield for Campylobacter was 3.71%, with 39 isolates recovered using CCDA medium compared with 13 using CampyBAP medium ( p ⬍ 0.0001) (Table 2). CCDA showed higher recovery of C. jejuni subsp. jejuni compared with CampyBAP (18/20 vs 8/20, respectively, p ⫽ 0.002). Although not fully identified to species, CCDA
TABLE 1 Frequency of Campylobacter Isolated from Pediatric Patients According to Age Age Group 0–1 1–2 2–3 3–4 4–5 5–6 Total
No. Isolates (Percent) 22 (52.4) 8 (19) 5 (11.9) 4 (9.5) — 3 (7.2) 42
showed higher recovery for isolates classified as Campylobacter species compared with CampyBAP (16/19 vs 3/19, p ⬍ 0.0001). There were no differences in the proportion of patients based on gender and isolation on CCDA (20 males, 19 females) or CampyBAP (7 males, 6 females). The results of this study are consistent with several previous studies showing that blood-free, charcoal-based medium such as CCDA is an excellent medium for the isolation of Campylobacter species from fecal samples (Endtz et al. 1991; GunMonro et al. 1987). Remarkably, CCDA recovered threefold more isolates than CampyBAP in the current study. CampyBAP is a blood containing medium containing a variety of antimicrobial agents including cephalothin. Cephalothin and other antibiotics, such as colistin and polymyxin B present in selective media may be inhibitory to some strains of C. jejuni and C. coli (Goossens et al. 1986; Ng et al. 1985; Ng et al. 1988) and will inhibit the growth of C. fetus subsp. fetus, thought to be under-isolated because of the use of cephalothin-containing media. Other species such as C. jejuni subsp doylei (Goossens et al. 1990), C. upsaliensis (Goossens et al. 1990), A. butzleri (Kiehlbauch et al. 1992; Kiehlbauch et al. 1991) generally will not grow on cephalothin containing media. None of the isolates that were tested with cephalothin disks in the current study appeared to be cephalothin susceptible so it is unlikely that the poor recovery of Campylobacter on CampyBAP was attributable to antimicrobial susceptibility of the isolates to cephalothin. In addition to the improved recovery of C. jejuni subsp. jejuni, CCDA recovered other Campylobacter species significantly better than CampyBAP (18 vs 3, p ⫽ 0.003). The identity of these species is unknown, but based on the predominance of C. jejuni subsp. jejuni as a cause of diarrheal disease, most of these isolates were likely to be C. jejuni subsp. jejuni. Only a few studies have evaluated multiple media for isolating Campylobacter in a prospective manner. Endtz et al (1991) evaluated five different selective media including CCDA and CampyBAP. As a single
Isolation of Campylobacter Species
331
TABLE 2 Identification of Campylobacter Species Isolated on CCDA and CampyBAP Media Identification
No. Isolates
No. Isolated CCDA Only
No. Isolated CampyBAP Only
No. Isolated Both Media
C. jejuni subsp. jejuni C. jejuni subsp. doylei C. coli C. lari Campylobacter species Total
20 1 1 1 19 42
12 0 1 0 16 29
2 0 0 0 1 3
6* 1 1 2** 10**
* p ⫽ 0.0022; ** p ⬍ 0.0001.
medium, CCDA had slightly better recovery of Campylobacter sp. than CampyBAP (83% vs 75%, respectively) and CCDA was superior in terms of ability to suppress normal contaminating enteric flora. CCDA was also better in recovering C. coli compared with CampyBAP (72% vs 42%). Gun-Munro et al (1987) also evaluated several common media used for isolating Campylobacter sp. including CampyBAP and CCDA. Quantitative studies and recovery from simulated stool samples showed that CCDA had better recovery than CampBAP, 99% vs 41%, respectively and CCDA also had better selective properties. Cefoperazone, which is used in CCDA as a selective agent, has been shown to have excellent suppressive properties of enteric flora, especially Pseudomonas (Endtz et al. 1991; Goossens et al. 1986; Gun-Monro et al. 1987). Other factors may have contributed to differences found in the performance of CampyBAP versus
CCDA is this study. Powdered media and supplements were obtained from different commercial suppliers and unknown storage conditions for these products may have had some affect on the performance of the media. Despite these concerns, however, the improvement of CCDA medium over CampyBAP is consistent with previously reported studies. Finally, the diagnosis of Campylobacter infections is highly dependent on the type of selective medium used in the laboratory. Our study shows that compared with the blood containing medium, CampyBAP, CCDA was a superior medium for routine use. Clearly, CampyBAP is an unacceptable medium for the routine use of Campylobacter in our population. Whether CCDA is superior to other blood containing formulations, such as Skirrows, CampyCVA, or charcoal media such as CSM, needs to be investigated.
REFERENCES Blaser MJ, Cravens B, Powers BW, Wang WL (1978) Campylobacter enteritis associated with canine infection. Lancet ii:979–981. Calva JJ, Ruiz-Palacios GM, Lopez-Vidal AB, Ramos A, Bojalil R (1988) Cohort study of intestinal infection with Campylobacter in Mexican children. Lancet i:503–505. Endtz HP, Ruijs GJ, Zwinderman AH, van der Reijden T, Biever M, Mouton RP (1991) Comparison of six media, including a semisolid agar, for the isolation of various Campylobacter species from stool specimens. J Clin Microbiol 29:1007–1010. Goossens H, De Boeck M, Coignau H, Vlaes L, Van den Borre C, Butzler J-P (1986) Modified selective medium for isolation of Campylobacter spp. from feces: Comparison with Preston medium, a blood-free medium, and a filtration system. J Clin Microbiol 24:840–843. Goossens H, Vlaes L, De Boeck M, Pot B, Kersters K, Levy J, de Mol P, Butzler JP, Vandamme P (1990) Is “Campylobacter upsaliensis”: An unrecognized cause of human diarrhoea? Lancet 335:584–586. Gun-Monro J, Rennie RP, Thornley JH, Richardson HL, Hodge D, Lynch J (1987) Laboratory and clinical eval-
uation of isolation media for Campylobacter jejuni. J Clin Microbiol 25:2274–2277. Hutchinson DN, Bolton FJ (1984) Improved blood free selective medium for the isolation of Campylobacter jejuni from faecal specimens. J Clin Pathol 37:956–957. Kiehlbauch JA, Baker CN, Wachsmuth IK (1992) In vitro susceptibilities of aerotolerant Campylobacter isolates to 22 antimicrobial agents. Antimicrob Agents Chemother 36:717–722. Kiehlbauch JA, Brenner DJ, Nicholson MA, Baker CN, Patton CM, Steigerwalt AG, Wachsmuth IK (1991) Campylobacter butzleri sp. nov. isolated from humans and animals with diarrheal illness. J Clin Microbiol 29: 376–385. Nachamkin I. (1999) Campylobacter and Arcobacter. In: Manual of Clinical Microbiology. Eds. Murray PR, Baron EJ, Pfaller MA, Tenover FC, and Yolken RH. Washington, D.C.: ASM Press, pp. 716–726. Nachamkin I, Barbagallo S (1990) Culture confirmation of Campylobacter spp. by latex agglutination. J Clin Microbiol 28:817–818.
332
Ng L-K, Stiles ME, Taylor DE (1985) Inhibition of Campylobacter coli and Campylobacter jejuni by antibiotics used in selective growth media. J Clin Microbiol 22: 510–514. Ng L-K, Taylor DE, Stiles ME (1988) Characterization of freshly isolated Campylobacter coli strains and suitability of selective media for their growth. J Clin Microbiol 26:518–523. Piersimoni C, Bornigia S, Curzi L, De Sio G (1995) Comparison of two selective media and a membrane filter technique for isolation of Campylobacter species from
P.A. Barbosa et al.
diarrhoeal stools. Eur J Clin Microbiol Infect Dis 14: 539–542. Ruiz-Palacios GM, Calva JJ, Pickering LK, Lopez-Vidal Y, Volkow P, Pezzarossi H, West MS (1990) Protection of breast-fed infants against Campylobacter diarrhea by antibodies in human milk. J Pediatr 116:707–713. Taylor DN (1992) Campylobacter infections in developing countries. In: Nachamkin I, Blaser MJ, & Tompkins LS, Eds. Campylobacter Jejuni: Current Status and Future Trends. Washington, D.C.: American Society for Microbiology, pp. 20–30.